1. PAPER RECYLING
Papermaking has been around for about 4,000 years. The Egyptians had a process of
making papyrus, a plant based paper product. The Chinese in the 2nd century BC had a
paper making process involving a fibrous matter. In the 8th century, Arabs had learned
the art of paper making, which explains the rise of their intellectual endeavors and
learning. It is one of those basic products that make our civilization what it is. But how
is it made? Although the process has been refined over the years, the process today is
less due to innovation than to efficiency of existing processes. It uses wood and it
consists of eight stages: debarking, chipping, pulping, bleaching, paper machine, blade
coater, supercalendar, and sheet converting.
Paper recycling is the process of recovering waste paper and remaking it into new
paper products. There are three categories of paper that can be used as feedstocks for
making recycled paper: mill broke, pre-consumer waste, and post-consumer waste. Mill
broke is paper trimmings and other paper scrap from the manufacture of paper, and is
recycled internally in a paper mill. Pre-consumer waste is material that was discarded
before it was ready for consumer use. Post-consumer waste is material discarded after
consumer use, such as old magazines, old newspapers, office waste, old telephone
directories, and residential mixed paper. Paper suitable for recycling is called "scrap
paper".
1) Sorting: Successful recycling requires clean recovered paper, so you must keep your
paper free from contaminants, such as food, plastic, metal, and other trash, which
make paper difficult to recycle. Contaminated paper which cannot be recycled must
be composted, burned for energy, or landfilled. Recycling centers usually ask that you
sort your paper by grade, or type of paper. Your local recycling center can tell you
how to sort paper for recycling in your community. To locate your nearest dealer,
look in the yellow pages of your phone book under "waste paper" or "recycling."
2) Re-pulping and Screening: The paper moves by conveyor to a big vat called a pulper,
which contains water and chemicals. The pulper chops the recovered paper into
small pieces. Heating the mixture breaks the paper down more quickly into tiny
strands of cellulose (organic plant material) called fibers. Eventually, the old paper
turns into a mushy mixture called pulp. The pulp is forced through screens containing
holes and slots of various shapes and sizes. The screens remove small contaminants
such as bits of plastic and globs of glue. This process is called screening
3) Cleaning:Mills also clean pulp by spinning it around in large cone-shaped cylinders.
Heavy contaminants like staples are thrown to the outside of the cone and fall
through the bottom of the cylinder. Lighter contaminants collect in the center of the
cone and are removed. This process is called cleaning.
4) Deinking: Sometimes the pulp must undergo a "pulp laundering" operation called
deinking (de-inking) to remove printing ink and "stickies" (sticky materials like glue
residue and adhesives). Papermakers often use a combination of two deinking
processes. Small particles of ink are rinsed from the pulp with water in a process
called washing. Larger particles and stickies are removed with air bubbles in another
process called flotation. During flotation deinking, pulp is fed into a large vat called a
flotation cell, where air and soap-like chemicals call surfactants are injected into the
pulp. The surfactants cause ink and stickies to loosen from the pulp and stick to the
air bubbles as they float to the top of the mixture. The inky air bubbles create foam
or froth which is removed from the top, leaving the clean pulp behind.
5) Refining, Bleaching and Color Stripping: During refining, the pulp is beaten to make
the recycled fibers swell, making them ideal for papermaking. If the pulp contains any
large bundles of fibers, refining separates them into individual fibers. If the recovered
paper is colored, color stripping chemicals remove the dyes from the paper.Then, if
white recycled paper is being made, the pulp may need to be bleached with
hydrogen peroxide, chlorine dioxide, or oxygen to make it whiter and brighter. If
brown recycled paper is being made, such as that used for industrial paper towels,
the pulp does not need to be bleached.
6) Papermaking: Now the clean pulp is ready to be made into paper. The recycled fiber
can be used alone, or blended with new wood fiber (called virgin fiber) to give it extra
strength or smoothness. The pulp is mixed with water and chemicals to make it
99.5% water. This watery pulp mixture enters the headbox, a giant metal box at the
beginning of the paper machine, and then is sprayed in a continuous wide jet onto a
huge flat wire screen which is moving very quickly through the paper machine.On the
screen, water starts to drain from the pulp, and the recycled fibers quickly begin to
bond together to form a watery sheet. The sheet moves rapidly through a series of
felt-covered press rollers which squeeze out more water. The sheet, which now
resembles paper, passes through a series of heated metal rollers which dry the
paper. If coated paper is being made, a coating mixture can be applied near the end
of the process, or in a separate process after the papermaking is completed. coating
gives paper a smooth, glossy surface for printing. Finally, the finished paper is wound
into a giant roll and removed from the paper machine. One roll can be as wide as 30
feet and weigh as much as 20 tons! The roll of paper is cut into smaller rolls, or
sometimes into sheets, before being shipped to a converting plant where it will be
printed or made into products such as envelopes, paper bags, or boxes.
7) Can all of my recovered paper be recycled?
8) As much as 80% of the content of typical recovered paper can actually be used in the
recycling process, but 20% cannot. A lot of what's contained in a bale of recovered
"paper" isn't paper! Trash, such as wire, staples, paper clips, and plastic, must be
removed during pulping, cleaning, and screening. This trash is usually sent to a
landfill, just like your trash at home.
9) Recovered paper contains some fibers which have become too small to be recycled
into paper. Your recovered paper may contain fibers which already have been
recycled one, twice, or perhaps several times! Wood fibers can only be recycled five
to seven times before they become too short and brittle to be made into new paper.
10) Recovered paper contains many other ingredients which are not paper fibers. Just
take a look at a magazine and you'll see what we mean. The printed pages contain
lots of ink. If the pages are shiny, that portably means they are coated with clay or
other materials. Magazines also contain adhesives which bind the pages together.
Ink, coatings, and adhesives must be removed from the paper before recycled paper
can be produced.
What can be made from recovered paper?
Most recovered paper is recycled back into paper and paperboard products. With a
few exceptions, recovered paper is generally recycled into a grade similar to, or of
lower quality than, the grade of the original product. For example, old corrugated
boxes are used to make new recycled corrugated boxes. Recovered printing and
writing paper can be used to make new recycled copy paper.
Recovered paper can be used in a variety of other products as well. Recycled pulp
can be molded into egg cartons and fruit trays. Recovered paper can be used for
fuel, ceiling and wall insulation, paint filler, and roofing. Nearly 100,000 tons of
shredded paper is used each year for animal bedding. Even cat litter can be made
from recovered paper!
2. POLYMERS AND PLASTICS
A polymer is a large molecule composed of repeating structural units. These units,
called monomers, are connected by covalent chemical bonds. A polymer may be a
natural or synthetic.
Plastics are materials made of long strings of carbon and other elements. Each plastic has
been developed for a special purpose.
Types of plastics depend on :
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the starting monomer selected,
the length of polymer chains,
the type of modifying compounds added.
a) POLYETYLENE
Annual production of 80 million tonnes. Used as packacking and plastic bags
b) PVC
Used in clothing and upholstery make flexible hoses and tubing, flooring electrical cable
insulation and used in waterbeds, toys, inflatable structures,…
c) POLYPROPYLENE
Used in a wide variety of applications like: Packagcing, textiles, loudspeakers automative
components, laboratory equipments, polymer banknotes and more…
d) POLYTETRAFLUOROETHYLENE
Brand name is Teflon, used as a non-stick coating for pans and other cookwares, used in
containers and pipework for reactive and corrosive chemicals, Reduces friction, wear and
energy consumption of machinery.
e) NYLON
First used commercially in a nylon-bristled toothbrush (1938) The first commercially
successful synthetic polymer used in so and so many applications.
WHY PLASTICS?
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Hard, tough and slippery
Soft and rubbery
Good insulators of heat or electricity
Light weight and flexible
Hygienic, cheap and non-rusting
Easy to shape and color
HEALTH EFFECTS ON HUMANS
PVC
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A known human carcinogen.
Commonly used to package foods and liquids, ubiquitous in children's toys and
teethers.
There is no ban in the use of PVC.
BISPHENOL A
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A chemical compound primarily used to harden plastic products including water
bottles even baby bottles.
Migrates from polycarbonate products into foods and beverages.
Even low doses of bisphenol A causes
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Brain damage
Hyperactivity
increased fat formation
early puberty
disrupted reproductive cycles.
PLASTIC POLLUTION ON EARTH
Oceanic Microplastics
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Plastics break into tiny pieces and stays in the ocean.
Ingested by every single organism in the world's oceans up to krill and right up to the
great Blue Whale.
As a result, plastic is transfered in the food chain.
Oceanic microplastics mix with the plankton.
A very heigh percentage of the worlds plankton feeders mistakenly inject it.
Scientists now nickname vast surface areas of the world's oceans as ‘’Plastic
EFFECTS ON MARINE ANIMALS
 Thousands of seabirds choke or get tangled in plastic debris.
 Plastic bag litter is lethal, killing many species including sea birds, whales, dolphins,
seals, seal lions and turtles every year.
Ingestion of litter such as plastic bags can cause
 physical damage,
 mechanical blockage of the oesophagus and digestive system
This results in
 a false sensation of fullness or satiation, as the litter may remain in the stomach.
 This can lead to internal infections, starvation and death.
3. DETERGENTS
Ancient Egyptians, Greeks and Moses used soap like materials also for the treatment of
different skin diseases as well as washing. In modern times, the usage of
soaps/detergents has become wide due to the importance of hygiene in reducing
pathogenic microorganisms.
1) Detergents
 They are sodium salts of long chain hydrocarbons.
 Prepared from petroleum or coal.
 Do not produce insoluble precipitates in hard water.
 Cleansing action is by surfactants.
 Some of are not biodegradable.
Structure of the soap:
2) Soaps
 They are metal salts of long chain higher fatty acids.
 prepared from vegetable oils and animal fats.
 cannot be used effectively in hard water as they produce scum i.e., insoluble
precipitates of Ca2+, Mg2+, Fe2+ etc.
 cleansing action is not as strong as that of detergents.
 biodegradable.
Structure of the detergents:
What are detergents?
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organic compounds which have both polar and non-polar characteristics
three types: anionic, cationic, and non-ionic
two kinds of detergents with different characteristics: phosphate detergents and
surfactant detergents
Detergents that contain phosphates are caustic, and surfactant detergents are toxic.
Surfactant detergents are used to enhance the wetting, foaming, dispersing and
emulsifying
Phosphate detergents are used to soften hard water and help suspend dirt in water
 Three types of energies are required for effective cleaning
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Chemical energy - Provided by a soap or detergent
Thermal energy - Provided by warm or hot water
Mechanical energy - Provided by a machine or hands
In cleaning process, the hydrophobic part interacts with dirt and hydrophilic part
interacts with water molecules. Surrounded dirt attracted by soap and dissolved
in water therefore leave the fabric.
Sources of Pollution
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The source of much of the pollution is said to be detergents
Dust present during production and transfer of the bulk powdered detergent can be
a serious problem
Detergents have a huge effect on water pollution
Not biodegradable since they are resistant to the action of biological agents
Tendency to produce stable foams in rivers
Tend to inhibit oxidation of organic substances present in wastewaters because they
form a sort of envelope around them
Changes in water quality with the high levels of phosphorus
the manufacturing method itself can be a problem because of wastes
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Pollutant ingredients are determined as:
Presence of phosphate
Presence of dyes
Presence of bleaching agents in the detergents.
Health Problems
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Human skin has lots of blood vessels and nerves, when the skin contacts with
chemicals, many health problems occur
Chemicals can be absorbed by all organs in the body in 26 seconds
According to some news detergents even cause sterility
If the companies prefer the cheaper chemicals and derivatives of petroleum may
result cancerogenic problems and acne and skin breakouts
Biting odour of detergents may cause some inhalation problems such as asthma
Chlorine in detergants may cause headhache, exhoustion and humidifier fewer
Health Problems
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To remove the disagreeable odour of chemicals, detergents have cheap, synthetic
and artificial fragrances
These products are added with preservatives and antibacterial agents (to increase
their shelf life) that make the detergents frequent causes of allergies and reactions
When companies use the cheaper materials, they can remain without disintegration
and goes the soil and river directly
And this threats the living organisms in those areas and the human being also
The chemical DDC used in detergents which is also not disintegrate and collects in the
nature, cause lots of environmental and health problems.
When the chlorine inside goes to canalization system it combines with other
chemicals and produce trihalomethane which is too dangerous
4. OZONE DEPLETION
The ozone layer protects the Earth from the ultraviolet rays sent down by the sun. If
the ozone layer is depleted by human action, the effects on the planet could be
catastrophic.Ozone is present in the stratosphere. The stratosphere reaches 30 miles
above the Earth, and at the very top it contains ozone. The suns rays are absorbed by
the ozone in the stratosphere and thus do not reach the Earth.
Ozone is a bluish gas that is formed by three atoms of
oxygen. The form of oxygen that humans breathe in
consists of two oxygen atoms, O2. When found on the
surface of the planet, ozone is considered a dangerous
pollutant and is one substance responsible for producing
the greenhouse effect.
The highest regions of the stratosphere contain about
90% of all ozone.
In recent years, the ozone layer has been the subject of
much discussion. And rightly so, because the ozone layer
protects both plant and animal life on the planet.
The fact that the ozone layer was being depleted was
discovered in the mid-1980s. The main cause of this is
the release of CFCs, chlorofluorocarbons.
Antarctica was an early victim of ozone destruction. A
massive hole in the ozone layer right above Antarctica
now threatens not only that continent, but many others
that could be the victims of Antarctica's melting icecaps.
In the future, the ozone problem will have to be solved so
that the protective layer can be conserved.
The Ozone Layer Over Time.
Image Credit: Institute for
Studies in Development,
Environment, and Security.
A. Causes of ozone depletion
Only a few factors combine to create the problem of ozone layer depletion. The production
and emission of CFCs, chlorofluorocarbons, is by far the leading cause. Many countries have
called for the end of CFC production because only a few produce the chemical. However,
those industries that do use CFCs do not want to discontinue usage of this highly valuable
industrial chemical. CFCs are used in industry in a variety of ways and have been amazingly
useful in many products. Discovered in the 1930s by American chemist Thomas Midgley,
CFCs came to be used in refrigerators, home insulation, plastic foam, and throwaway food
containers. Only later did people realize the disaster CFCs caused in the stratosphere. There,
the chlorine atom is removed from the CFC and attracts one of the three oxygen atoms in
the ozone molecule. The process continues, and a single chlorine atom can destroy over
100,000 molecules of ozone. In 1974, Sherwood Rowland and Mario Molina followed the
path of CFCs. Their research proved that CFCs were entering the atmosphere, and they
concluded that 99% of all CFC molecules would end up in the stratosphere. Only in 1984,
when the ozone layer hole was discovered over Antarctica, was the proof truly conclusive.
At that point, it was hard to question the destructive capabilities of CFCs. Even if CFCs were
banned, problems would remain. There would still be no way to remove the CFCs that are
now present in the environment. Clearly though, something must be done to limit this
international problem in the future.
B. Effects of ozone depletion
Even minor problems of ozone depletion can have major effects. Every time even a small
amount of the ozone layer is lost, more ultraviolet light from the sun can reach the Earth.
Every time 1% of the ozone layer is depleted, 2% more UV-B is able to reach the surface of
the planet. UV-B increase is one of the most harmful consequences of ozone depletion
because it can cause skin cancer. The increased cancer levels caused by exposure to this
ultraviolet light could be enormous. The EPA estimates that 60 million Americans born by
the year 2075 will get skin cancer because of ozone depletion. About one million of these
people will die. In addition to cancer, some research shows that a decreased ozone layer will
increase rates of malaria and other infectious diseases. According to the EPA, 17 million
more cases of cataracts can also be expected. The environment will also be negatively
affected by ozone depletion. The life cycles of plants will change, disrupting the food chain.
Effects on animals will also be severe, and are very difficult to foresee. Oceans will be hit
hard as well. The most basic microscopic organisms such as plankton may not be able to
survive. If that happened, it would mean that all of the other animals that are above
plankton in the food chain would also die out. Other ecosystems such as forests and deserts
will also be harmed. The planet's climate could also be affected by depletion of the ozone
layer. Wind patterns could change, resulting in climatic changes throughout the world.
C. Solutions of ozone depletion
The discovery of the ozone depletion problem came as a great surprise. Now, action
must be taken to ensure that the ozone layer is not destroyed.Because CFCs are so
widespread and used in such a great variety of products, limiting their use is hard. Also,
since many products already contain components that use CFCs, it would be difficult if
not impossible to eliminate those CFCs already in existence.The CFC problem may be
hard to solve because there are already great quantities of CFCs in the environment.
CFCs would remain in the stratosphere for another 100 years even if none were ever
produced again.Despite the difficulties, international action has been taken to limit
CFCs. In the Montreal Protocol, 30 nations worldwide agreed to reduce usage of CFCs
and encouraged other countries to do so as well.However, many environmentalists felt
the treaty did "too little, too late", as theNatural Resources Defense Council put it. The
treaty asked for CFC makers to only eliminate half of their CFC production, making some
people feel it was inadequate.By the year 2000, the US and twelve nations
in Europe have agreed to ban all use and production of CFCs. This will be highly
significant, because these countries produce three quarters of the CFCs in the
world.Many other countries have signed treaties and written laws restricting the use of
CFCs. Companies are finding substitutes for CFCs, and people in general are becoming
more aware of the dangers of ozone depletion.
5.
AIR POLLUTION
Air is the ocean we breathe. Air supplies us with oxygen which is essential for our
bodies to live. Air is 99.9% nitrogen, oxygen, water vapor and inert gases. Human
activities can release substances into the air, some of which can cause problems for
humans, plants, and animals.
HISTORY OF AIR POLLUTION
 Industrial Revolution during the 18th and 19th centuries was based on the use of
coal.
 In the Middle Ages the use of coal in cities such as London was beginning to
escalate.
 Industriess were often located in towns and cities, and together with the
burning of coal in homes for domestic heat, urban air pollution levels often
reached very high levels.
 During the first part of the 20th century, tighter industrial controls lead to a
reduction in smog pollution in urban areas
TYPES OF AIR POLLUTION
a. Indoor Air Pollution
Many people spend large portion of time indoors - as much as 80-90% of their
lives. We work, study, eat, drink and sleep in enclosed environments where air
circulation may be restricted.
For these reasons, some experts feel that most of the people suffer from the
effects of indoor air pollution more than outdoor pollution.
Tobacco smoke, cooking and heating appliances, and vapors from building
materials, paints, furniture, etc. cause pollution inside buildings.
b. Outdoor pollution
Smog is a type of large-scale outdoor pollution. It is caused by chemical
reactions between pollutants derived from different sources, primarily
automobile exhaust and industrial emissions.
CAUSES OF AIR POLLUTION
There are many different chemical substances that contribute to air pollution. These
chemicals come from a variety of sources.Among the many types of air pollutants are
nitrogen oxides, carbon monoxides, and organic compounds that can evaporate and enter
the atmosphere.Air pollutants have sources that are both natural and human. Now, humans
contribute substantially more to the air pollution problem.Forest fires, volcanic eruptions,
wind erosion, pollen dispersal, evaporation of organic compounds, and natural radioactivity
are all among the natural causes of air pollution.Usually, natural air pollution does not occur
in abundance in particular locations. The pollution is spread around throughout the world,
and as a result, poses little threat to the health of people and ecosystems.Though some
pollution comes from these natural sources, most pollution is the result of human activity.
The biggest causes are the operation of fossil fuel-burning power plants and automobiles
that combust fuel. Combined, these two sources are responsible for about 90% of all air
pollution in the United States.Some cities suffer severely because of heavy industrial use of
chemicals that cause air pollution. Places like Mexico City and Sao Paulo have some of the
most deadly pollution levels in the world.
EFFECTS OF AIR POLLUTION
Air pollution is responsible for major health effects. Every year, the health of countless
people is ruined or endangered by air pollution.Many different chemicals in the air affect the
human body in negative ways. Just how sick people will get depends on what chemicals they
are exposed to, in what concentrations, and for how long.Studies have estimated that the
number of people killed annually in the US alone could be over 50,000.Older people are
highly vulnerable to diseases induced by air pollution. Those with heart or lung disorders are
under additional risk. Children and infants are also at serious risk.Because people are
exposed to so many potentially dangerous pollutants, it is often hard to know exactly which
pollutants are responsible for causing sickness. Also, because a mixture of different
pollutants can intensify sickness, it is often difficult to isolate those pollutants that are at
fault.Many diseases could be caused by air pollution without their becoming apparent for a
long time. Diseases such as bronchitis, lung cancer, and heart disease may all eventually
appear in people exposed to air pollution.Air pollutants such as ozone, nitrogen oxides, and
sulfur dioxide also have harmful effects on natural ecosystems. They can kill plants and trees
by destroying their leaves, and can kill animals, especially fish in highly polluted rivers.
SOLUTIONS OF AIR POLLUTION
Air pollution has many disastrous effects that need to be curbed. In order to accomplish
this, governments, scientists and environmentalists are using or testing a variety of methods
aimed at reducing pollution.
There are two main types of pollution control.
Input control involves preventing a problem before it occurs, or at least limiting the effects
the process will produce.Five major input control methods exist. People may try to
restrict population growth, use less energy, improve energy efficiency, reduce waste, and
move to non-polluting renewable forms of energy production. Also, automobile-produced
pollution can be decreased with highly beneficial results.
Output control, the opposite method, seeks to fix the problems caused by air pollution. This
usually means cleaning up an area that has been damaged by pollution.
Input controls are usually more effective than output controls. Output controls are also
more expensive, making them less desirable to tax payers and polluting industries.Current
air pollution control efforts are not all highly effective. In wealthier countries, industries are
often able to shift to methods that decrease air pollution. In the United States, for example,
air pollution control laws have been successful in stopping air pollution levels from rising.
However, in developing countries and even in countries where pollution is strictly regulated,
much more needs to be done.
6.
WATER POLLUTION
Sources of water pollution:
 Industry is a huge source
 Produces pollutants harmful to people and the environment
 Many use freshwater to carry away waste from the plant and into rivers, lakes and
oceans.
Some of the sources of pollution are:
 Lead
 Mercury
 Nitrates
 Phosphates
 Sulphur
 Oils
 Petrochemicals
 Nuclear wastes
Environmental and health risks of water Pollution:
 All types of water pollution are harmful to the health of humans and animals
 May not damage our health immediately but can be harmful after long term
exposure
 Heavy metals can accumulate in nearby lakes and rivers
 Are toxic to marine life such as fish and shellfish
 Subsequently to the humans who eat them
 Can slow development; result in birth defects and some are carcinogenic
 Industrial waste contains many toxic compounds
 damage the health of aquatic animals and those who eat them
 Some toxins may only have a mild effect whereas other can be fatal
 They can cause immune suppression, reproductive failure or acute poisoning
 Microbial pollutants result in infectious diseases
 Infect aquatic life and terrestrial life through drinking water
 Major problem in the developing world
 Cholera and typhoid fever
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Organic matters and nutrients causes an increase in aerobic algae
Depletes oxygen from the water column
Causes the suffocation of fish and other aquatic organisms
Suspended particles in freshwater reduces the quality of drinking water
Reduce the amount of sunlight penetrating the water
Disrupting the growth of photosynthetic plants and micro-organisms
SOIL POLLUTION
Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals,
salts, radioactive materials, or disease causing agents, which have adverse effects on plant
growth and animal health.
Soil is the thin layer of organic and inorganic materials that covers the Earth's rocky surface.
The organic portion, which is derived from the decayed remains of plants and animals, is
concentrated in the dark uppermost topsoil. The inorganic portion made up of rock
fragments, was formed over thousands of years by physical and chemical weathering of
bedrock. Productive soils are necessary for agriculture to supply the world with sufficient
food.
There are many different ways that soil can become polluted, such as:
• Seepage from a landfill
• Discharge of industrial waste into the soil
• Percolation of contaminated water into the soil
• Rupture of underground storage tanks
• Excess application of pesticides, herbicides or fertilizer
• Solid waste seepage
The most common chemicals involved in causing soil pollution are:
• Petroleum hydrocarbons
• Heavy metals
• Pesticides
• Solvents
Types of Soil Pollution
• Agricultural Soil Pollution
• Soil pollution by industrial effluents and solid wastes
• Pollution due to urban activities
Causes of Soil Pollution
Soil pollution is caused by the presence of man-made chemicals or other alteration in the
natural soil environment. This type of contamination typically arises from the rupture of
underground storage links, application of pesticides, percolation of contaminated surface
water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct
discharge of industrial wastes to the soil. The
most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead
and other heavy metals. This occurrence of this phenomenon is correlated with the degree
of industrialization and intensities of chemical usage.
A soil pollutant is any factor which deteriorates the quality, texture and mineral content of
the soil or which disturbs the biological balance of the organisms in the soil. Pollution in soil
has adverse effect on plant growth.
Pollution in soil is associated with
• Indiscriminate use of fertilizers
• Indiscriminate use of pesticides, insecticides and herbicides
• Dumping of large quantities of solid waste
• Deforestation and soil erosion
i. Indiscriminate use of fertilizers
Soil nutrients are important for plant growth and development. Plants obtain carbon,
hydrogen and oxygen from air and water. But other necessary nutrients like nitrogen,
phosphorus, potassium, calcium, magnesium, sulfur and more must be obtained from the
soil. Farmers generally use fertilizers to correct soil deficiencies. Fertilizers contaminate the
soil with impurities, which come from the raw materials used for their manufacture. Mixed
fertilizers often contain ammonium nitrate (NH4NO3), phosphorus as P2O5, and potassium
as K2O. For instance, As, Pb and Cd present in traces in rock phosphate mineral get
transferred to super phosphate fertilizer. Since the metals are not degradable, their
accumulation in the soil above their toxic levels due to excessive use of phosphate fertilizers,
becomes an indestructible poison for crops.
The over use of NPK fertilizers reduce quantity of vegetables and crops grown on soil over
the years. It also reduces the protein content of wheat, maize, grams, etc., grown on that
soil. The carbohydrate quality of such crops also gets degraded. Excess potassium content in
soil decreases Vitamin C and carotene content in vegetables and fruits. The vegetables and
fruits grown on overfertilized soil are more prone to attacks by insects and disease.
ii. Indiscriminate use of pesticides, insecticides and herbicides
Plants on which we depend for food are under attack from insects, fungi, bacteria, viruses,
rodents and other animals, and must compete with weeds for nutrients. To kill unwanted
populations living in or on their crops, farmers use pesticides. The first widespread
insecticide use began at the end of World War II and included DDT
(dichlorodiphenyltrichloroethane) and gammaxene. Insects soon became resistant to DDT
and as the chemical did not decompose readily, it persisted in the environment. Since it was
soluble in fat rather than water, it biomagnified up the food chain and disrupted calcium
metabolism in birds, causing eggshells to be thin and fragile. As a result, large birds of prey
such as the brown pelican, ospreys, falcons and eagles became endangered. DDT has been
now been banned in most western countries. Ironically many of them including USA, still
produce DDT for export to other developing nations whose needs outweigh the problems
caused by it. The most important pesticides are DDT, BHC, chlorinated hydrocarbons,
organophosphates, aldrin, malathion, dieldrin, furodan, etc. The remnants of such pesticides
used on pests may get adsorbed by the soil particles, which then contaminate root crops
grown in that soil. The consumption of such crops causes the pesticides remnants to enter
human biological systems, affecting them adversely. An infamous herbicide used as a
defoliant in the Vietnam War called Agent Orange (dioxin), was eventually banned. Soldiers'
cancer cases, skin conditions and infertility have been linked to exposure to Agent Orange.
Pesticides not only bring toxic effect on human and animals but also decrease the fertility of
the soil. Some of the pesticides are quite stable and their bio- degradation may take weeks
and even months. Pesticide problems such as resistance, resurgence, and heath effects have
caused scientists to seek alternatives. Pheromones and hormones to attract or repel insects
and using natural enemies or sterilization by radiation have been suggested.
iii. Dumping of solid wastes
In general, solid waste includes garbage, domestic refuse and discarded solid materials such
as those from commercial, industrial and agricultural operations. They contain increasing
amounts of paper, cardboards, plastics, glass, old construction material, packaging material
and toxic or otherwise hazardous substances. Since a significant amount of urban solid waste
tends to be paper and food waste, the majority is recyclable or biodegradable in landfills.
Similarly, most agricultural waste is recycled and mining waste is left on site.
The portion of solid waste that is hazardous such as oils, battery metals, heavy metals from
smelting industries and organic solvents are the ones we have to pay particular attention to.
These can in the long run, get deposited to the soils of the surrounding area and pollute
them by altering their chemical and biological properties. They also contaminate drinking
water aquifer sources. More than 90% of hazardous waste is produced by chemical,
petroleum and metal-related industries and small businesses such as dry cleaners and gas
stations contribute as well.
Solid Waste disposal was brought to the forefront of public attention by the notorious Love
Canal case in USA in 1978. Toxic chemicals leached from oozing storage drums into the soil
underneath homes, causing an unusually large number of birth defects, cancers and
respiratory, nervous and kidney diseases.
iv.
Deforestation
Soil Erosion occurs when the weathered soil particles are dislodged and carried away by
wind or water. Deforestation, agricultural development, temperature extremes,
precipitation including acid rain, and human activities contribute to this erosion. Humans
speed up this process by construction, mining, cutting of timber, over cropping and
overgrazing. It results in floods and cause soil erosion. Forests and grasslands are an
excellent binding material that keeps the soil intact and healthy. They support many habitats
and ecosystems, which provide innumerable feeding pathways or food chains to all species.
Their loss would threaten food chains and the survival of many species. During the past few
years quite a lot of vast green land has been converted into deserts. The precious rain forest
habitats of South America, tropical Asia and Africa are coming under pressure of population
growth and development (especially timber, construction and agriculture). Many scientists
believe that a wealth of medicinal substances including a cure for cancer and aids, lie in
these forests. Deforestation is slowly destroying the most productive flora and fauna areas in
the world, which also form vast tracts of a very valuable sink for CO2.
Pollution Due to Urbanisation
Pollution of surface soils
Urban activities generate large quantities of city wastes including several Biodegradable
materials (like vegetables, animal wastes, papers, wooden pieces, carcasses, plant twigs,
leaves, cloth wastes as well as sweepings) and many non-biodegradable materials (such as
plastic bags, plastic bottles, plastic wastes, glass bottles, glass pieces, stone / cement pieces).
On a rough estimate Indian cities are producing solid city wastes to the tune of 50,000 80,000 metric tons every day. If left uncollected and decomposed, they are a cause of
several problems such as
• Clogging of drains: Causing serious drainage problems including the burst / leakage of
drainage lines leading to health problems.
• Barrier to movement of water: Solid wastes have seriously damaged the normal
movement of water thus creating problem of inundation, damage to foundation of buildings
as well as public health hazards.
• Foul smell: Generated by dumping the wastes at a place.
• Increased microbial activities: Microbial decomposition of organic wastes generate large
quantities of methane besides many chemicals to pollute the soil and water flowing on its
surface
• When such solid wastes are hospital wastes they create many health problems: As they
may have dangerous pathogen within them besides dangerous medicines, injections.
Pollution of Underground Soil
Underground soil in cities is likely to be polluted by
• Chemicals released by industrial wastes and industrial wastes
• Decomposed and partially decomposed materials of sanitary wastes
Many dangerous chemicals like cadmium, chromium, lead, arsenic, selenium products are
likely to be deposited in underground soil. Similarly underground soil polluted by sanitary
wastes generate many harmful chemicals. These can damage the normal activities and
ecological balance in the underground soil
Effects of Soil Pollution
Agricultural
• Reduced soil fertility
• Reduced nitrogen fixation
• Increased erodibility
• Larger loss of soil and nutrients
• Deposition of silt in tanks and reservoirs
• Reduced crop yield
• Imbalance in soil fauna and flora
Industrial
• Dangerous chemicals entering underground water
• Ecological imbalance
• Release of pollutant gases
• Release of radioactive rays causing health problems
• Increased salinity
• Reduced vegetation
Urban
• Clogging of drains
• Inundation of areas
• Public health problems
• Pollution of drinking water sources
• Foul smell and release of gases
• Waste management problems
Environmental Long Term Effects of Soil Pollution
When it comes to the environment itself, the toll of contaminated soil is even more dire. Soil
that has been contaminated should no longer be used to grow food, because the chemicals
can leech into the food and harm people who eat it.
If contaminated soil is used to grow food, the land will usually produce lower yields than it
would if it were not contaminated. This, in turn, can cause even more harm because a lack of
plants on the soil will cause more erosion, spreading the contaminants onto land that might
not have been tainted before. In addition, the pollutants will change the makeup of the soil
and the types of microorganisms that will live in it. If certain organisms die off in the area,
the larger predator animals will also have to move away or die because they've lost their
food supply. Thus it's possible for soil pollution to change whole ecosystems
8.
GLOBAL WARMING
Glaciers are melting, sea levels are rising, cloud forests are drying, and wildlife is scrambling
to keep pace. It's becoming clear that humans have caused most of the past century's
warming by releasing heat-trapping gases as we power our modern lives. Called greenhouse
gases, their levels are higher now than in the last 650,000 years.
We call the result global warming, but it is causing a set of changes to the Earth's climate, or
long-term weather patterns, that varies from place to place. As the Earth spins each day, the
new heat swirls with it, picking up moisture over the oceans, rising here, settling there. It's
changing the rhythms of climate that all living things have come to rely upon.
What will we do to slow this warming? How will we cope with the changes we've already set
into motion? While we struggle to figure it all out, the face of the Earth as we know it—
coasts, forests, farms and snow-capped mountains—hangs in the balance.
Greenhouse effect
The "greenhouse effect" is the warming that happens when certain gases in Earth's
atmosphere trap heat. These gases let in light but keep heat from escaping, like the glass
walls of a greenhouse.
First, sunlight shines onto the Earth's surface, where it is absorbed and then radiates back
into the atmosphere as heat. In the atmosphere, “greenhouse” gases trap some of this heat,
and the rest escapes into space. The more greenhouse gases are in the atmosphere, the
more heat gets trapped.
Scientists have known about the greenhouse effect since 1824, when Joseph Fourier
calculated that the Earth would be much colder if it had no atmosphere. This greenhouse
effect is what keeps the Earth's climate livable. Without it, the Earth's surface would be an
average of about 60 degrees Fahrenheit cooler. In 1895, the Swedish chemist Svante
Arrhenius discovered that humans could enhance the greenhouse effect by making carbon
dioxide, a greenhouse gas. He kicked off 100 years of climate research that has given us a
sophisticated understanding of global warming.
Levels of greenhouse gases (GHGs) have gone up and down over the Earth's history, but they
have been fairly constant for the past few thousand years. Global average temperatures
have stayed fairly constant over that time as well, until recently. Through the burning of
fossil fuels and other GHG emissions, humans are enhancing the greenhouse effect and
warming Earth.
Scientists often use the term "climate change" instead of global warming. This is because as
the Earth's average temperature climbs, winds and ocean currents move heat around the
globe in ways that can cool some areas, warm others, and change the amount of rain and
snow falling. As a result, the climate changes differently in different areas.
Aren't temperature changes natural?
The average global temperature and concentrations of carbon dioxide (one of the major
greenhouse gases) have fluctuated on a cycle of hundreds of thousands of years as the
Earth's position relative to the sun has varied. As a result, ice ages have come and gone.
However, for thousands of years now, emissions of GHGs to the atmosphere have been
balanced out by GHGs that are naturally absorbed. As a result, GHG concentrations and
temperature have been fairly stable. This stability has allowed human civilization to develop
within a consistent climate.
Occasionally, other factors briefly influence global temperatures. Volcanic eruptions, for
example, emit particles that temporarily cool the Earth's surface. But these have no lasting
effect beyond a few years. Other cycles, such as El Niño, also work on fairly short and
predictable cycles.
Now, humans have increased the amount of carbon dioxide in the atmosphere by more than
a third since the industrial revolution. Changes this large have historically taken thousands of
years, but are now happening over the course of decades.
Why is this a concern?
The rapid rise in greenhouse gases is a problem because it is changing the climate faster than
some living things may be able to adapt. Also, a new and more unpredictable climate poses
unique challenges to all life.
Historically, Earth's climate has regularly shifted back and forth between temperatures like
those we see today and temperatures cold enough that large sheets of ice covered much of
North America and Europe. The difference between average global temperatures today and
during those ice ages is only about 5 degrees Celsius (9 degrees Fahrenheit), and these
swings happen slowly, over hundreds of thousands of years.
Now, with concentrations of greenhouse gases rising, Earth's remaining ice sheets (such as
Greenland and Antarctica) are starting to melt too. The extra water could potentially raise
sea levels significantly.
As the mercury rises, the climate can change in unexpected ways. In addition to sea levels
rising, weather can become more extreme. This means more intense major storms, more
rain followed by longer and drier droughts (a challenge for growing crops), changes in the
ranges in which plants and animals can live, and loss of water supplies that have historically
come from glaciers.
Scientists are already seeing some of these changes occurring more quickly than they had
expected. According to the Intergovernmental Panel on Climate Change, eleven of the
twelve hottest years since thermometer readings became available occurred between 1995
and 2006.